Voltage-regulator.



M PFEFFE-R VOLTAGE REGULATOR.

APPLICATION IEILBD JAN. 14, 1910.

1,054,937, Patented Mar. 4, 1913.

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6 law Fig. l.

WITNESSES fzvyzgzraa 2 M MAXM HLLIN PPEFFEH;

9. 246; w glwq libs .ITTbRNEl M. PEEFFER. VOLTAGE REGULATOR.

APPLICATION TILED JAN. 14, 1910.

1,054,937. Patented Mar/1, 1913.

2. w JMS IXIMILIAN PfEFFEH= I .teni; Fig. 3

UNITED STATES PATENT OFFICE.

MAXIMILIAN PFEFFER, OF VIENNA, AUSTRIA-HUNGARY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

VOLTAGE-REGULATOR.

Specification 0! Letters Patent.

Patented Mar. 4, 191 3.

Application filed January 14, 1910. Serial No. 537,993.

a subject of the Emperor of Austria-Hungary, residing at Vienna, AustrialIun ary,'

have invented certain new and uset'ul lmprovcments in Vol.age-Regulators, of which the following is a specification.

My invention relates to a system of antomatically maintaining a predetermined distribution of load on a plurality of alternating current generators operating in parallel, the excitation of which is controlled by auton'latic potential regulators.

\Vhcn a number of alternating current generators are operating in parallel, a phase displacement is apt to occur between the currents of the generators due to differences of excitation. lVhen separate regulators are used for the separate generators, the operation is more or less indefinite. The terminal voltage can be maintained by all the regulators operating together, or by one, or a few doing all the regulation. If one rcgulator' only does all the regulation, then the excitation of its generator only will be changed and its current, therefore, will be out of phase with the currents of the other generators, if they were in phase when the regulator began to act. Since the electrical and mechanical characteristics of the generators and the regulators cannot be identical, the regulation will usually be effected by one or a few regulators, giving inefficient operation, accompanied by the exchange of equalizing currents among the machines.

It is the aim of the present invention to bring about at all times a proper phase relation of the currents by making the regulator of each machine sensitive not only to changes of voltage but also to the changes of the phase angle between current and p r i the magnet 18 of the regulator. lhe secvoltage in the armature leads of its particular machine.

I In the accompanying drawings, Figure 1 i illustrates my invention in its simplest form as applied to alternating current gencr- I ators operating in parallel and controlled by Tirrill regulators: Fig. 2 illustrates a mod|-- lied system in which the regulators are also influenced by changes of load on the is a tragmental view showing the connections which are suitable when my invention is to be applied to a system opcrating with an inherently low power factor, I

Referring to Fig. l. the three-phase genpotential and current transformers. If the erators, l, 2 are coimected to the main busbars 3, .4, 5 by means of lead wires 6, 7, 8 and 9, 1O, 11 respectively. Only two generators have been illustrated, but it will be understood that my invention is applicable to any number of generators operating in parallel. As the connections and arrangement of parts used with the generator 1 are v exactly identical with those used with generator 2, it will sufiice to explain my inven tion with reference to generator 1 only.

The generator is provided with a separately excited field 12 which is fed by means of an exciter 1c. The shunt field lat of the oxciter is in series with a manually operated rheos'tat 15 which is periodically short cireuited by the vibrations of the Tirrill regulator l6,'in a well understood manner. The mgulator consists of the usual direct magnet 17 connected across the excitcr mains and the alternating current magnet 18, the connections of which will be explained presently. The vibrations of the magnets 17, [S of the regulator periodically open and close the circuit of one of the ditlerential windings of the relay magnet 19, which rapidly makes and breaks the contacts 90 in a shunt circuit around the resistance 15, thus inserting and withdrawing the resistance 15 in the field circuit of the eXciter as is wtzll uiulcrstood.

The primary of the potential transformer 2-1 connected across two of the generator leads 6, 7. The primary circuit of a current'transformer is in series with the third lead 8. An adjustable resistance 23 is connected across the secondary of the current transformer The secondary of the current trausforuu-r is connected in series with an adjustable resistance 26, to the conductors 24, 25, leading to the winding of ondary oi the potential transformer 21., in series with the adjustable resistance 27, is likewise connected to the lincsl-i, 25, in parallel with the secondary of the current transformer. This connection secures a 90 phase displacement between the secondary voltage of transformer .21 and the secondary voltage of transformer 22 whenever the currents in the. generator leads are in phase with the voltage. The current in the mag net 18 is therefore due to the resultant, or rather average. of the two voltages of ,the

current differs in phase from the voltage of the generator, then the two voltages of transformers 2t and 232 are not 90 apart, but more or less. depending whether the current lags or leads, and the resultant current,

therefore, in leads Q-l, 25 is less or more than at unity power factor. lzleru-e, with a lag gmg or leading current the regulator caused to act, to raise or lower the field ex 3 citation of the exciter and thus in turn that of the generator. In practice the resistance 23 15 so ad usted that the current from the transformer 22 amounts to onl) a small fraction of an ampere. The series resistance 26 and 97 make it possible to connect the secondaries of the. transformers Bl,

in parallel, thereby combining their currents and avoiding the necessiti" at using separate windings in the magnet. 18.

\Vith the arrangement and connection as above iescrihed, if the regulators are set it maintain an equal phase relation between the current and voltage of the machines. and

the current of any machine tends to get out.

of phase, its regulator will be affected by the change of phase angle between the current and voltage in its generator leads, and it will act to raise or lower the excitation of its generator in the manner already 'described. For example, if one of the genera-tors is overexcited, the resulting change of phase angle between its current and voltage will increase the current in the regulator magnet, in the above described manner, and lower the excitation of the generator.

Should it be desired for some reason to maintain a predetermined difference of phase between the generator currents, the

regulators are initially set to maintain a predetermined difference of excitation, and will then regulate for a deviation from the predetermined excitation of any of the machines.

\Vhile the above system has been described only in connection with three-phase generators it will. be understood that it can likewise be applied to asingle phase system, the proper displacement of phase between the current and voltage being artificially produced by the combination of resistance and reactance, as is well understood in the art.

In the system illustrated by Fig. 2 the regulators are similarly affected by phase displacement of the currents thus tending to preserve equal phase relations, butin this case the regulator is likewise made responsive to an increase of load on the system to which the parallel connected generators contribute current. This is accomplished by placing a current transformer in one of the main line conductors 28, 29, 30,-in this case in conductor 28. Across the secondary of this current transformer 31 is placed an ad- 5 l with the secondaries of t ansformers 21, 22 l and in wries with the resistance 33. The 1 connection should be made in such manner that the transformer 31 will be in opposition to the transformer 22. Therefore, with a rising load on the main line the currents of i transformer 31 and of the t'ansformer in each of the generator leads may so combine, that the ell'cct of the regulators will be to raise the excitation of the gene ators so as to give a constant. terminal voltage at some I distant point.

If nrv invention is to be applied to a system operating with an inherently low power actor, say below 0.75, I consider it advisable to place the primar of .the current trans- I former 22 in one of the conductors to which the. primary of the potential transformer 2t is connected; this is indicated in Fig. 3.

With a considerable phase displacement between the current and voltage in the generator leads, the two transformer voltages Eare not approximately 90 apart, as they would he at non-imluctive load but a e more nearly in phase. Any further change, therefore, in the phase of the current would not greatly change the resultant current in the main regulator magnet, and hence the regulator would be relatively sluggish. By shifting the current transformer into another lead and so shifting its current by 60 its voltage becomes approximately 90 displaced from the voltage of the potential transformer at this low power factor, and the regulator is rendered more sensitive for this kind of load.

hat I claim as new and desire to secure by Letters Patent of the. United States, is

l. The combination of a plurality of alternating current generators connected in parallel, a voltage regulator for eaelrof said generators, and means for making said regulators responsive to change of phase relation between the electromotive forces and the currents in the lines of their respective generators.

2. The combination of a plurality of alternating current generators connected in parallel, a voltage regulator for each of said generators, containing a main control magnet supplied with current, one component of which bears a fixed phase relation to the voltage across two of the phase legs, and another component of which bears a fixed phase relation to the current in one leg.

The combination of a plurality of alternating currentgenerators operating in parallel, a voltage regulator for each of said generators, said regulator being responsive to changes of phase relation between voltage and current in the circuit of its own generator and to changes of current in the 1 main line into which all the generators feed. i 4. The crunbination of a plurality of alterl nating current generators connected in parallel, a roltage regulator for each of the Said 1 relation to the current in the main line into generators containing a main control mag which all the generators feed.

net supplied with current, one component of In witness whereof, I have hereunto set which bears a fixed phase relation to the my hand this 20th day of December, 1909.

voltage of its generator armature, another MAXIMILIANPFEFFER. component. of which bears. a fixed phase rei W itnesses: lation to the current of its armature and AUGUST FUGGER,

another component of which bears a fixed ROBERT W. HmNcAR'rnER. 

